1. Field of the Invention
The present invention relates to a mobile machine for aspirating ballast from a ballast bed supporting a track consisting of rails fastened to ties having opposite ends at shoulders of the ballast bed, which comprises a machine frame extending in a longitudinal direction and supported by undercarriages running on the track, and mounted on the machine frame a ballast aspirating device comprising a short suction inlet pipe defining a suction inlet port, and a ballast excavating device vertically adjustable by drive means linking the ballast excavating device to the machine frame, the ballast excavating device being pivotal about a vertical axis in an operating position for transporting the excavated ballast to the suction inlet port.
2. Description of the Prior Art
British patent No. 2,172,326 discloses such a machine, which comprises a screening installation for cleaning the aspirated ballast removed from the ballast bed. The aspirating device comprises three suction inlet pipes arranged on the machine frame and connected to a compressor by suction hoses. The machine frame is a trailer supported by its own undercarriage on the track and is displaceable relative to a continuously advancing chassis, and the three suction inlet pipes are arranged adjacent each other in a transverse direction so that they may engage the ballast in the same crib in an operating position adjacent a tie. They are vertically and transversely adjustable. A unit for loosening the ballast and to convey it to the suction opening is connected to the lower end of each suction inlet pipe, for which purpose the ballast loosening units are equipped with raking tines and rotatable scraping wheels which are affixed to the end of a horizontal, elongated housing, and the housing is rotatable about a vertical axis. In operation, the ballast loosening units are oriented parallel to the ties, are lowered into a crib to a level below the ties and then rotated in a horizontal plane 90.degree.. In this way, the units engage the ballast below the ties while they are displaced in the crib in the longitudinal direction of the ties. The loosened ballast is aspirated through the suction openings and is either conveyed to the screening installation for cleaning and then redistributed to the ballast bed, or it is entirely removed by a conveyor arranged below the air lock if it is desired to lower the track level. The guidance and drives for the ballast loosening units involve complex structures wherefore the operating efficiency and speed of the machine are relatively low even though the machine advances continuously along the track.
The mobile machine for excavating a ballast bed disclosed in published German patent application No. 2,226,612 comprises a ballast excavating device arranged at each side of the machine frame, each ballast excavating device comprising a beam on which a revolving endless excavating chain is mounted. The beams are vertically adjustable and pivotal about an axis at one of their ends. In a rest position, they are pivotal upwardly about a horizontal axis extending transversely to the machine frame. In operation, the ballast excavating devices are lowered into the ballast on the track shoulders and are then pivoted from both shoulders into the ballast bed under the track. The revolving excavating chains convey the excavated ballast towards the shoulders whence an upwardly inclined conveyor arrangement moves the ballast to a screening installation for cleaning.
U.S. Pat. No. 4,938,239 discloses a suction arrangement for cleaning a track bed, which comprises a suction head having an inlet port, a suction conduit connecting a ventilator to the suction head to create suction at the inlet port and a receptacle incorporating a filter connected to the suction conduit. A compressed air generating arrangement is associated with the suction head and forms a closed pressure-suction system therewith, this arrangement comprising a compressed air discharge nozzle arranged within the inlet port and a compressed air conduit connecting the nozzle to a compressor.